On Other Worlds
by Rukia Siry
Summary: Maybe a lot of things change, but no matter what roads they walk, the most important parts of them will always stay the same. /hamabros&co, au collection. latest update: It's a sunny late afternoon in downtown Fransokyo, and Hiro definitely isn't expecting to meet a ghost.
1. ageswap

_re: ageswap au_

 _in which hiro is the elder and tadashi is a high school shrimp._

\- (●—●) -

"I'm older, so I get the side near the door," Hiro declares.

"I'm younger, so I get the bigger half of the room," Tadashi retorts.

Aunt Cass looks between them. She pinches the bridge of her nose. She sighs.

"I'm also more mature," Tadashi says, cheeks pinched like he's trying not to sound desperate. "Mentally."

"Hey!"

"It's true." A reluctant grunt of assent.

"Come on, Aunt Cass!" Hiro pleads. "I have the floor plan all thought out and everything!"

Oh, she's seen the floor plan. It involves a mattress with a built-in trampoline function and a secret room hidden behind the second wall shelf. Tadashi's plans for the room are only slightly better.

"Ahahaha, no. I'm not falling for that." Aunt Cass turns away to briefly scan the cafe through the curtain. The morning rush has already passed. It doesn't look like anyone needs help.

So right now she has two arguing boys to deal with, both of who want the lion's share of the freshly renovated room upstairs.

Trying to mediate is kind of hard when she's also trying very hard not to laugh.

"Tell you what. How about I just give the whole attic to Mochi, and you two can fight over the living room couch?"

Hiro instantly ditches the pout for a horrified expression. "Aunt Cass, you're gonna pick the cat over your beloved nephews?"

Tadashi nudges his elbow. "Over _you_."

"Shut up, _brother younger_."

"I think this is my win, because Mochi likes me way more. Sorry, big bro. Looks like it's the couch for you."

"Hey, hey. If this is a fight we're talking about, I've been able to bench you since… wow. Ever. I don't like your odds, Dashi."

Now it was Tadashi's turn to redden furiously and stomp off towards the kitchen. "I'm six years younger and like a hundred pounds, what did you expect?"

"Is that wet or dry?"

Tadashi breathes deeply - _don't freak out, don't shriek, you're not your crazy grad student brother_ -

"You're a terrible person and I hope you die."

There. He even managed to say it nicely.

"Not before I hit Schneider's human anatomy lecture!" Hiro throws cheerfully over his shoulder. He's already walking past Tadashi, backpack dangling from one arm and halfway to the door.

"Have fun in high school, nerdling. I hear it's the best years of your life."

"I'm still getting that room!" Tadashi shouts after him.

—

"I'm not getting the room," Tadashi moans.

He slumps over one of the outdoor picnic tables that usually get monopolized by senior upperclassmen and groans loudly. Wasabi pats his back consolingly. Fred's off standing in line for more of the dried-out travesties that the school calls chicken nuggets. Honey Lemon and Gogo sit across from them, trying vainly to hold back laughter.

"Look. Smaller rooms - sections - are easier to clean anyways. Plus, you have a lot of light coming in, and that's the best thing, right? Beds are for sleeping, not eating, or drinking, or doing homework -"

"I won't brush the eraser shreds onto the sheets again, okay?" Gogo grumbles. "It's a habit, didn't mean it, didn't know that you'd be such a pansy over it-"

"They're pink and dirty and microscopic! I'm pretty sure there're still some hiding in the cracks-"

"Stop arguing," Tadashi mumbles. "It's a partition. Not even the whole room. I'm arguing over five-eighths of a room. Who does that?"

"You and your brother, apparently." Gogo shrugs. "Honey, your input?"

Honey Lemon shrugs. "I can sympathize. My older brother and sister waged daily wars over who would be the first to use the bathroom in the mornings."

Wasabi's eyebrow shoots up. "Wait. What about you?"

Honey flashes them a brilliant smile. "Oh. I always got there first."

Gogo muffles a snort. Tadashi muffles what might loosely be called a wheeze.

"I woke up every morning at five-thirty a.m. for a year," Honey adds thoughtfully.

Wasabi nods cautiously. "That's… dedicated."

"Such is life."

"Guys? Back to the bedroom thing?" Tadashi reminds them. "How in the world do I convince Aunt Cass to give me the room?"

He lifts his head a little off the table, ticking off the fingers of one hand. "Hiro's older, he's stronger, he outweighs me by like fifty pounds, he's got his black belt, he's a genius who went to college when he was freaking fourteen, how do I start to compete with that?"

"Don't say that!" Honey reproves. "You're - really nice, and smart, and everyone likes you. Come on, be positive. What do you have?"

Tadashi's expression told her that was the wrong question. "Let's see. I'm a fourteen year old shrimp. I skipped a grade, but hey. We all did. I'm good at math, but wow, so is Hiro. In fact, he's so good that he skipped five grades and took a year off to do whatever he wanted after that -"

"Yeah, that's enough," Wasabi says. Honey Lemon looks appropriately abashed.

"…What about chores?" she tries to salvage. "Whoever washes more dishes, works the register, the like?"

"Me and Hiro already work shifts in the cafe in our free time."

"Suck up to Aunt Cass," Gogo says. Honey elbows her. "What? It'd be hilarious to watch."

"Helpful advice, Gogo."

"Yeah, yeah."

Fred plops a double serving of chicken crisps on the table right before he flops across the rest of the seating space afforded by the picnic bench. Honey Lemon nudges his foot off her knee.

"Hey, dudes, dudettes. What'd I miss?"

"Tadashi's angsting over who gets the bigger half of the attic room," Wasabi summarizes.

"Did you seriously spend six bucks on this stuff?" Gogo says, stealing a nugget. She bites into it and grimaces.

"You can see the individual salt grains on it," Honey notes, looking morbidly fascinated.

"Sodium," Fred corrects. "You need it to stay alive."

"It dries you up when you get too much of it."

" _Science_."

Gogo mutters something unintelligible. Fred switches his attention to Tadashi, who hasn't moved from his spot.

"Look, old friend. I see your misery. I feel your pain. And lucky for you, I have your solution!"

He leans forward a little. Wasabi and Honey Lemon lean forward a little. Gogo's bored expression doesn't change.

"Duel with swords. After the example of the late Japanese dynasts."

Fred pauses, then adds thoughtfully, "You can use mops instead."

" _Fred_." From four throats.

"What?"

—

"Mr. Hamada."

"Professor Callaghan!"

Hiro flips back the welding mask and turns to greet the person standing at the door.

"Making progress? I know you've about finished your microbots research. Are you planning on furthering that avenue, or…?"

"I'm thinking about going for the neurocranial transmission aspect," Hiro says. "I've been taking some biology classes. I think there's something to be said for biorobotic optical emulation. Still have a ton of stuff to look into, but it's possible." He presses the end of his pencil against his cheek, lost in thought.

Callaghan chuckles, and Hiro hears the door open again. "In that case, I'll leave you to it. Good luck, Hiro."

"Right," Hiro says absently, flipping to a fresh page of graph paper. "Thanks."

—

Hiro comes in with a bang.

A literal bang. The back door slams open and Hiro whisks up the stairs into the living area, tossing his backpack on the kitchen counter and going through the kitchen cabinets.

"Hi, Hiro," Tadashi says listlessly.

"Evening, nerd. Are the bowls in the dishwasher clean?"

"Yep."

"Excellent." Hiro snatches up a bowl, runs a finger around the rim, nods in satisfaction. "What'd Aunt Cass whip up?"

"Table." There's chicken and rice, which is pretty standard. "Aunt Cass's downstairs running the beat poetry circle. She wants us to help clean up in the kitchen when we're done eating."

"Sure."

Tadashi doesn't look up from stirring his cold noodles with a chopstick, but he hears the sound of a chair getting pulled up and loud chewing noises, so he assumes Hiro's eating.

Great. Hiro's even the bigger glutton, for crying out loud. Can't he win at anything?

So Hiro's eating rice and chomping like he doesn't have a care in the world, and Tadashi thinks that if he sits and stews in his cesspool of misery for any longer, he might actually explode.

Hiro's eating, but he looks up when Tadashi slams his palm down on the table.

"Mmff? 'Daush?"

"I've made my decision."

Hiro swallows the mouthful of chicken and rice and reaches for his fork. "What's up?"

"You can have the bigger half."

His brother looks up, cheeks bulging. "Hrf? What're you talkin' bout?"

Tadashi pauses. Then he aims the most scorching glare he can muster at Hiro. "You know, the room? Up in the attic? Don't tell me you've forgotten _already_!"

The steak knife slices through the meat. "Uh, wow. That was easy."

"I've made my decision." Tadashi throws up his hands. "I have weighed every possible option. Every viable path. And it's hopeless. I can't win. I'm never going to get the room."

He waves his hand at the ceiling. "So go on. Take it. It's up there. Gift wrapped. Waiting."

He waits a second, staring up at the ceiling.

A second passes. Then two. Tadashi sneaks a glance back at Hiro, wondering if he's said something wrong. Or weird.

Then he hears him chuckle.

Hiro snorts again. And again. And then he's full-out laughing, gasping and wheezing over his dinner so loudly that Tadashi momentarily wonders whether his older brother's having a seizure.

" _That's_ what you've been so worked up about?" Hiro gets out. "I come in today and you're pushing your noodles around looking like the walking dead. You haven't said a word all through dinner. And then-!" More laughing. Tadashi's too nonplussed to interject.

"So… okay, go be weird. What about the room?"

"Dude," Hiro snorts, "You can have the room. Or the bigger half. Whatever, if you're that worked up about it. It's no big deal."

Tadashi stares. "… Seriously?"

"I mean, it's not gonna be the end of the world if I don't get three more cubic feet of space to shove my junk. I've got the garage for that anyways…"

"But -" Tadashi stutters, thinking wait, wait, wait just a second - "What about the contest? The fight, the, uh -"

He takes one look at the giggles that Hiro is epically failing at containing and feels the blood rush to his face. "Come on, knucklehead! I was freaking out about this all day, the least you could do is tell me why you're laughing your HEAD OFF!"

At least his tone manages to shock some degree of sense back into Hiro, who pauses to catch his breath while still trying valiantly to stop his sides from shaking. "Okay, okay, serious mode. This was all just for fun. I know you're the worryholic and all that, but hey. This isn't something you should be worrying about."

Hiro grins at him. Tadashi subsides in embarrassment, suddenly feeling the need to look everywhere but at his older brother.

"But… I dunno. It seems like you've got it all, sometimes. You're older, you're smarter. I want to be like that, too, okay? How do I match that?"

Tadashi doesn't see Hiro get up, engrossed with the tabletop as he is, but he does feel the older Hamada ruffle his hair. He swats ineffectually at Hiro's hand. "Stop it!"

"Never."

"Urgh."

Hiro laughs again, and then his face is serious as he bends down to look Tadashi right in the eye. "Look, nerdling. Maybe I've got brainy, but you've still got a lot of growing to do. Plus, you're already pretty darn great the way you are."

"…Really?"

"For starters, you're a lot better at being polite," Hiro says, counting them off on his fingers. "You've got lots of friends, not that running cutting-edge research isn't just as awesome. You're super smart and probably way nicer than I could ever be, and -" Hiro ruffles his hair again. "You're my nerdy little brother. How's that?"

"… You're way too cheesy, cheese."

"That's the spirit." Hiro hops to his feet, energy standing out in the way he does the familiar little hop-skip to the stairs. "So you get the room - the bigger bit, anyways - and I get the room and the garage. Now that's settled, what do you say we go help Aunt Cass close up the cafe?"

Tadashi feels a grin spread across her face. "You're on."

He's not his brother. He's not a genius.

But that doesn't mean he's any less.

\- (●—●) -

 **A/N: So this is basically a bunch of random Big Hero 6 au ficlets that aren't really related at all, except when they are. I'll be transferring a bunch over from tumblr at first, but it's nice having them all in one place.**


	2. maze runner 1

_re: maze runner au_

 _Tadashi's only been here a day, but he's fairly sure that tracking deadly, faceless creatures across an empty labyrinth is never a good idea._

 _But Hiro and Gogo, they're Runners. They know the maze better than anyone. Things will turn out fine._

 _Right?_

\- (●—●) -

"It's getting late."

Wasabi crossed his arms, his shoulders tense where he leaned against one of the supports of the straw pavilion.

"They should have been back by now."

Tadashi followed Wasabi's gaze to the distant gray of the Maze entrance, then shielded his eyes to gaze up at the morning sun. He was terrible at reading time, but noon had passed a long time ago, and the horizon had a faintly reddish tint. Worry tugged at his nerves.

Late afternoon had come and gone. Hiro and Gogo still hadn't returned.

Tadashi paced nervously back and forth, acutely aware of the growing chill in the air. "Can't you send someone after them?"

Some of the other boys had started to mill about the gathering area, and Tadashi was sure that he wasn't the only one who noticed the absence. Gogo was a constant, reassuring presence in the Glade, and Hiro was the youngest. Both had been there as long as almost everyone could remember. Literally.

"We can't risk losing anyone else," was the response, and Tadashi read the unease encapsulated in the man's low voice.

"But-"

"He's right, Tadashi."

He hadn't noticed Honey Lemon approaching. She nodded to Wasabi. "Even if we send someone in now… even if they find them, they won't have time to get out of the maze. Gogo and Hiro are our best runners. They'll make it."

Tadashi was pretty sure he already knew the answer to the next question. He asked anyways.

"What happens if they don't?"

Wasabi didn't respond. Honey Lemon filled in the gap.

"They're going to make it."

"But what if-"

" _They're going to make it."_ Honey Lemon's voice quavered on the last syllable. Tadashi let it go, feeling guilty.

"They're going to make it," he repeated instead, and tried to believe it.

Late afternoon dragged into early evening. The wind picked up, gusting briskly into the valley where lighter breezes had broken against those insurmountable walls.

The sun began to disappear over the horizon, and no one could pretend lack of worry anymore.

Tadashi crowded close to the Maze entrance along with what seemed like the rest of the Glade - twenty or thirty skinny and pale-faced older teenagers. Fred, the boy who ran construction and cracked terrible jokes, paced back and forth next to a pale-faced Honey Lemon. Wasabi was a statue against the wall, but his fingers twitched and his eyes flickered back and forth across the Maze entrance, and what little they could see of its interior.

Nothing. And now they were all here with the light fading and an unnatural breeze picking up amongst the catacombs of the Maze.

Tadashi barely knew Hiro, and his experience of Gogo had primarily consisted of the right hook that had knocked his name back into his head. But the thought of them stranded on the other side made his gut twist.

 _No one survives a night in the maze._

Tadashi felt a sickening weight settle in his stomach.

The walls groaned, and Tadashi instinctively covered his face. All around him, the other Gladers were doing the same as a wind that smelled of wet soil and sludge and rot gusted out of the Maze mouth like the breath of some monstrous beast. Tadashi lowered his arm. The grinding of stone against stone echoed in his ears.

"Oh no," he whispered.

The doors were closing, inching shut, and Tadashi only saw the barren gloom of the vines that climbed the wall and where _were they_ -

"There!" someone shouted. Tadashi's heart leapt into his throat as two shapes rounded the corner.

It was them. He'd recognize that fluffy mop anywhere. But-

"Something's wrong."

The two shadows weren't separating. Hiro listed, staggering to the side as he struggled to keep a limp Gogo slung over his back. Sweat ran down the younger's red face in rivulets, and his arms and legs shook with the strain.

No wonder they had taken so long to get back. Hiro had been carrying Gogo all the way.

They were moving at a snail's pace, but the gates weren't so kind. The right and left sides of the wall marched towards each other, ten-foot-thick behemoths that threatened to cut them off for good.

"They're not going to make it," Wasabi breathed.

Honey Lemon's voice was quiet and morbidly intense. Tadashi almost jumped when it came from almost right beside his ear. "Yes, they _are._ Hiro, run! You can do it!"

Her voice rang across the short distance between them, clear and sharp, and Tadashi saw Hiro raise his head, sides heaving with effort, and marshal his strength for one last, desperate sprint.

That was the catalyst. Everyone started shouting, cheering, gesturing frantically.

" _Run_ , kid!"

"Nearly there, go for it!"

"You've gotta leave her!"

Hiro whipped his head violently back and forth in denial, but he was already flagging. Tadashi felt the first spike of horror when a step, shakier than the last, finally dislodged Gogo from his back. She slumped to the ground, and Hiro seized her by the arms to drag her towards the doors, three-quarters closed and still moving.

Wasabi was right. They weren't going to make it.

Tadashi saw Hiro's approaching figure in the dwindling gap between the two doors. He saw the boy nearly doubled over in exhaustion, sides heaving and still raggedly pulling both of them towards the exit, but too little, too late

He saw them, and

he

moved.

"Tadashi-!"

"You shuck, don't-"

Tadashi moved. He sprinted forward even as voices shouted after him, even as hands reached out to drag him back by the sleeves-

Too late. The cold stone of the walls pressed in ever closer, and as they scraped the width of his shoulders, Tadashi pressed his palms flat against the walls and shuffled on. He could barely see them through the gap, and icy rock pressed against his neck and shoulders -

His hands met open air. Tadashi threw himself through the gap and collapsed against the tiles, just as the final vestiges of light disappeared behind him.

The doors ground closed, and the sudden stop cut off everything.

Everything, save for the sound of their wheezes in the yawning silence.

Tadashi locked eyes with Hiro, five feet away, and felt his heart sink when he saw the frozen despair reflected in the younger boy's eyes.

Hiro fell to his knees, cheeks flushed and gasping for breath. Gogo was still limp and silent behind him, but the teen didn't make a second effort to steady her.

"Good job, idiot," he choked. "Now we're all going to die."

\- (●—●) -

 **A/N: tbc. If you liked it enough/saw room for improvement, review?**


	3. maze runner 2

_re: maze runner au_

 _continuation: They're stuck in the Maze, and even though Tadashi really wants to believe they can all make it out of here alive, observable evidence seems to point otherwise._

\- (●—●) -

"What do you _mean_ , we're all dead?"

Tadashi staggered up, casting his gaze about the walls that surrounded them. The stamps of his feet against the stone were an oddly reassuring break to the eerie quiet that had settled the instant the doors swung shut.

Hiro, on the other hand, hadn't moved an inch. He just sat on his haunches, staring at the door like he was still waiting for it to reopen.

Tadashi's voice, however, seemed to jerk him back to his senses. He rounded on the older boy with enough force to make Tadashi jerk back on reflex.

"What do you think it means?" Hiro snapped. "We're stuck, Greenie. We're as good as gone."

It had only been a minute or two of rest at most, but Hiro looked like he was starting to get his breath back. Unfortunately, most of his energy was now devoted to yelling at Tadashi.

"This is the maze. No one's ever survived a night in here!" Hiro gestured behind him, to the place where the entrance branched in two. "Honestly? I don't know what you were thinking - oh, wait. You weren't."

Tadashi didn't know what to say to that. What _could_ he say? The doors were closing, and Hiro had needed help, and -

Someone had to. Help, that is.

 _What were you even going to do_? The voice pushed insistently at the edge of his thoughts. _What were you going to accomplish by locking yourself in here?_

He was going to help. Somehow. In some way. Tadashi sighed, let it go.

"Well-" He glanced around. Vines climbed only part of the way up the walls here, but they were thick and probably grew in bigger clumps farther in. Hiro followed his gaze with something like resignation. "What can we do? Isn't there somewhere we can hide in here, or a place we can go-"

"Are you even listening to me? There's _nowhere to go_. This is the maze. Once the doors close, the Grievers come out. And then it's game over."

"How did this even happen?" Tadashi blurted out. Hiro drew in a sharp breath, as if to yell at him some more. And then the teen seemed to crumple, shoulders slumping and eyes falling to the wet stones.

"… She jumped in front of me."

" _What_?"

Hiro wouldn't meet Tadashi's gaze. "We found the Griever, and it looked dead, just lying there with half its insides on the ground. I - I was a stupid, cocky bonehead. I got too close."

He looked up, and his eyes were hollow. "It came to life. Gogo pushed me out of the way. I got a scraped knee, and she got stung. Okay?"

Tadashi opened his mouth. Paused. Closed it.

Hiro apparently took it as a dismissal. He sank slowly to the ground, his head in his hands. His voice cracked when he spoke.

"I couldn't leave her. I knew we couldn't both make it back, but… I couldn't."

Tadashi had only been here for a day. He didn't know the leaders and the people here, not like Hiro did. He wasn't Honey Lemon or Fred, who could comfort pretty much anyone with a hug or dumb joke - Tadashi had been on the receiving end of some more than once during the day. He wasn't Wasabi or Gogo either, who offered reassurance just by being _there_.

He didn't know what to say. Was there anything that could be said to make this better?

Tadashi edged forward to put a hesitant hand on Hiro's shoulder. It didn't get shrugged off. "I might have done the same thing," he offered.

Hiro snorted, tone acidic. "You ran in here, didn't you?"

The Maze groaned, sparse leaves and grit eddying through the passage before them. Hiro visibly flinched, jerking away.

"What am I doing -? There's no time! We have to go!" His voice, an octave higher than Tadashi had ever heard it, cracked on the last word. Hiro's face had turned gray, and his eyes darted back and forth as if searching for something in the shadows.

The boy paced where he stood. "O-Okay. Here's what we're gonna do. We're gonna get Gogo somewhere else - anywhere - and then we're gonna run. We're going to not get killed, we're going to get out alive -"

His voice was rising successively higher with every word, and his movements got more and more erratic until Tadashi finally just grabbed his arms.

"Whoa, whoa. Calm down."

Hiro shook his head, his eyes unfocused. "I - we have to get out of here. We're boxed in as it is. We can't stay here any longer." The teen squeezed his eyes shut, but they shot open again with something very close to panic. "Who am I kidding?" Hiro blurted out. "We're all gonna die!"

Tadashi switched his grip to Hiro's shoulders and shook him. Hard. The boy stilled, staring back at him with wide eyes. " _Look_ , Hiro. If I'm not giving up, you _definitely_ don't get to. Neither of us are giving up on each other. Got it?"

Hiro's eyes finally focused, and he met Tadashi's gaze. Tadashi nodded slowly, willing Hiro to calm down. He _needed_ calm right now, or else he might start losing it too-

Hiro's breath steadied, and he nodded shakily back. Tadashi let out a breath.

"O-okay." And then Hiro shoved him away. "Alright. Calm. I guess."

He paused, then reluctantly added, "Thanks. Greenie."

"No… problem." Tadashi's voice trailed off as something registered at the edge of his vision - over Hiro's shoulder, where the Maze forked and splintered into the darkness. He squinted.

Hiro's eyes followed him as he walked past him, staring into the dark. "What are you looking at?"

The vines. Even fifteen or twenty meters in, they grew thick on the walls, and they only got denser the deeper inward they went.

Maybe they couldn't climb them. But maybe they didn't have to.

"Hey, Hiro."

"Hm?"

"Those vines. How much weight can they hold?"

* * *

"This is crazy."

"Pull!" Tadashi hissed.

They heaved on the vine. Gogo hovered just a little higher, almost invisible behind the leaves that overgrew the wall. She hadn't woken up even as they'd carried her deeper into the maze.

"That's a good thing," Hiro had said when Tadashi brought it up. "Remember Shang? She'd probably try to kill us."

Tadashi thought about the way Gogo had taken him down during the campfire fight and figured that she'd most likely succeed.

"Okay, that's good enough," Hiro muttered. Tadashi shook his head. "One more pull. Then we tie it off."

"There's no _time_ -" Hiro snapped, and then he stopped.

In fact, he let go of the vine so quickly that Tadashi stumbled and nearly fell, grunting with effort as he tried to hold the vine with just his own weight. Gogo jerked and dropped a couple of feet. Tadashi regained his footing and pulled harder. "Hiro, what are you _doing_ -?"

Hiro didn't answer. Tadashi turned to look at him, an irritated comment bubbling up in the back of his throat.

"… Hiro?"

The younger boy's arms had dropped bonelessly to his sides, and his face was rapidly turning gray. Tadashi felt his stomach drop like a rock.

"Too late," Hiro croaked.

A bloodcurdling screech echoed down the passageway, followed by an insect-like clicking noise that raised the hairs on the back of Tadashi's neck. He turned his head mutely, following Hiro's horrified gaze to the shadow emerging at the end of the corridor.

The first thing he thought was _spider._

It looked like one, anyways, with segmented legs that gleamed metallic in the Maze half-light. The body that connected them, though, was anything but arachnid, a fleshy mass that dripped with fluid and glistened dully with every movement. It opened its mouth, and Tadashi realized that the lopsided slash in its body is its mouth - a yawning maw dripping with saliva and needle-sharp teeth.

Tadashi didn't need Hiro's harsh intake of breath to know that this was a Griever.

He especially didn't need any prompting to realize that this would be a _really good time_ to run.

A quick glance up at Gogo, and Tadashi knew he couldn't.

 _Someone has to help._ It felt like he'd said it once. Maybe more than once, but the phrase came to mind like an old friend. Or maybe more like an executioner, considering the situation he'd gotten himself into because of it.

Hiro had abandoned all pretense of calm, if he'd ever had any in the first place. He skittered sideways, eyes dilating in terror, fixed on the slowly approaching shape.

"This isn't working," he breathed. His gaze switched frantically from the dark shape of the Griever, to Tadashi, to Gogo, dangling high above.

"Just help me tie it off!" Tadashi hissed back, struggling with the vine. His heart dropped the second he saw Hiro shaking his head back and forth, like there was something in there trying to escape.

"Just -" Hiro swallowed, backing up slowly. " _Hide_."

And he ran.

He ran, and Tadashi saw the moment the Griever's tiny, gleaming eyes snapped to the single moving figure in its field of vision, saw the moment its intent became clear.

The Griever _screamed_ , the wires in its half-metal body snapping taut even as it barreled forward towards them. Tadashi instinctively half-rolled, half-dove to the side, scrabbling against the wall, for a handhold, anything _._ In a second his body was engulfed with soft tendrils of overgrown moss, the lingering smell of wet rot in his nostrils and leaves tickling his ears.

The vines grew thick at the bottom, he realized. Thick enough to cover him completely. Thick enough to _hide_.

The Griever didn't notice him, huddling in the dirt like a worm afraid of sunlight. The Griever didn't notice Gogo, unconscious and good as invisible within the backdrop of tangled foliage.

Instead, it scuttled forward, moving absurdly fast despite its lopsided anatomy. Hiro disappeared around a corner in the murky gloom, the Griever following - Tadashi ducked as one leg drilled a hole in the wall above his head. Dust and pebbles showered the back of his neck.

The creature rounded the corner. The clicking of its spindly legs and metallic shrieks faded into the distance, until Tadashi could hear only the occasional distant screech. He didn't dare to move - dared even to breathe.

He waited. How long, he couldn't tell. A minute? Ten? Maybe an hour. Tadashi honestly couldn't tell.

No screams - no _human_ screams. That was good, right?

 _Maybe Hiro screamed and you couldn't hear him_ , a voice whispered. _Maybe he's already dead_.

He pushed the thought away.

Within moments, Tadashi had scrambled to his knees within his temporary shelter, cold fingers working clumsily to secure the vine that held Gogo in the air. He looped it twice around one of the lower hanging ones and jerked it as hard as he could to tighten it.

And then, cautiously, let go.

The vine held. Tadashi breathed an enormous sigh of relief.

That caught in his throat as the familiar clicking sound once again resounded down the corridor.

Tadashi froze and, unable to resist the temptation, edged the tiniest bit forward, peering out from his hiding spot.

Halfway down the passage, a second Griever creaked out of a branching passageway. Tadashi pressed a hand to his mouth to muffle any noise and hunkered down, pressing his face into the dirt. Stay quiet, stay still. If it worked the first time, it could work again, right?

 _The first time Hiro distracted it. The first time it had another target._

The Griever moved slowly, almost sedately. A metal limb clacked against stone a foot away from Tadashi's hand.

He held still. The fleshy sack contracted for a moment, then expanded. The Griever swiveled. Tadashi held his breath and prayed that it would leave.

A second later, he found himself staring into a trio of beady, lifeless eyes.

Its maw opened wide, and Tadashi screamed.

A leg dented rock an inch from his neck. Tadashi rolled to the side, scrambling clumsily to his feet even as the Griever backed out of the thicket and plunged after him.

Tadashi ran, his heart pounding in his ears, thudding to the beat of his boots against the stone under his feet. It wasn't a matter of drawing it away from Gogo anymore. It wasn't a matter of _anything_ at all -

He was terrified, and his panic gave him the energy to run like he never had before.

The Griever screeched behind him, and he looked back only to nearly stumble as the monster snapped at his heels -

Another Griever landed in a clatter and tuneless shriek before him. Tadashi yelled in shock and stuttered to a stop, ducking into the nearest open corridor and picking up the pace.

He lost track of where he was headed after that. It was turn after turn, desperate backpedaling at dead ends and passages that didn't end, wind rushing past him. His gasps echoed harshly in the silence between the Grievers' shrill chattering, the burning of his legs and lungs, the squelch of slimy shoes on slick ground.

It was only as he slowed momentarily at a fork that another force smashed into him. Tadashi thrashed on instinct, only stilling when hands seized his shoulders in an iron grip.

"You're crazy!" Hiro sputtered, face inches away and red with exertion. "Absolutely nuts, you son of a -" He cut himself off abruptly. "I know a way to get them off our backs. Follow me!"

He took off like a bullet from a gun, and Tadashi followed, too conscious of the single remaining Griever at his back. Had the others given up? Gotten lost? Tadashi had no idea.

'There!" Hiro shouted up ahead. Tadashi felt a jolt of hope as he saw a closing wall up ahead, and he understood Hiro's plan in a heartbeat. They could run through, trap the Griever on the other side.

They might come out on top of this _alive_.

He didn't realize Hiro had stopped until Tadashi blew straight past him.

* * *

" _Hiro!"_ The Idiot Greenie called. He'd stalled in the middle even as the walls closed in, though Hiro could see him backing up towards the other end as the space got smaller and smaller.

"What are you _doing_? Get over here!"

"I have a plan!" he shouted back. A stupid idea. A really stupid idea, except tonight seemed to be the time for crazy plans, and if a greenie like Tadashi could pull off something like this Hiro _definitely could-_

 _Who am I kidding? This is crazy. This is absolutely nuts, and we're all gonna die if I don't pull this off._

Hiro breathed in deeply. The panic that had permeated his mind when the doors had first closed, when the Griever had been chasing him was still there, and a night full of similar horrors had done nothing at all to dull it. It was still there in the black spots crowding the edge of his vision, in the voice chanting _run, get out here NOW_ in the back of his mind, but Hiro refused to let it take over. Not this time.

Maybe it was the effect of having someone else there. Maybe it was just that he wasn't alone. Whatever it was, it gave Hiro the strength to shove the fear down and fill deadly purpose in its place.

Too late to rethink this, anyways. The Griever rounded the corner, mandibles clicking as it galloped towards them. Hiro waited, heart in his throat, hyperaware of the grinding of stone behind him.

A hundred feet away. Fifty. Twenty.

 _Now_.

"Come and get me, freak!" Hiro yelled, and the Griever shrieked back, a grating sound that tore at his eardrums. Hiro didn't stop to listen.

He turned and ran _,_ sprinting between the walls towards the end. The Griever, unwilling to let its prize escape so easily, dove into the gap after him without even a moment of hesitation, claws moving from ground to wall as the space narrowed, legs tearing pebble showers and grooves in the stone.

He could see Tadashi up ahead, screaming something that rang hoarse and indecipherable in his pounding ears, muffled by the screeching behind him. Hiro felt a _whoosh_ of air behind him and ducked on instinct, leaning into his sprint. The tip of a stinger tickled the hairs on his head, and if possible, Hiro ran faster.

 _I can do this. I can do this._

Tadashi was _right there_ , and he knew the Griever was only feet behind him with the walls closing in.

He was almost out.

Hiro heard the sickening crackscream _squelch_ the moment he threw himself into Tadashi, still going full-pelt. They went tumbling head over heels onto wet stone, the walls grinding to a halt after them-

And Hiro figured crazy ideas really did pay off, after all.


	4. the twilight zone

_re: ghost/reincarnation/bad end au_

 _In which a poor undergrad student stumbles into a lot that's been abandoned for years and meets a ghost instead. Maybe Hiro's been on this earth for sixteen short years, but this guy has walked (floated?) here for quite a while longer. Too long, if you asked either of them._

\- (●—●) -

"So you're a ghost," Hiro says.

"Well. Yeah, I guess so," the ghost says. He looks quite well for someone dead a hundred years gone.

"Are you like a generic ghost?" Hiro presses. He steps a little closer, reaching out to wave his hand through the guy's body. The guy hastily steps (floats?) back before Hiro can touch him, bobbing up several feet.

"Please don't do that," he says, voice a little strained.

"Sorry," Hiro responds absently. "Like a ghost random, or an angry vengeful ghost, or Moaning Myrtle-like?" He's fascinated by how the guy hovers in the air like he's swimming through water. It could be a hologram, but the way he'd thrown those bullies down like that ruled that out. Maybe it was electromagnetism? Or density lighter than air?

"… Definitely not Moaning Myrtle. Let's just go with ghost. Plain ghost. Is Harry Potter still a thing? It's been like two hundred years." The ghost floats back down. Sits down in midair. Crosses his legs.

Hiro shakes his head. " Dude, HP's like Shakespeare. Timeless. Derek brings it up all the time." For some reason he'd almost slipped up and called his friend by his whole name, Frederick, though he had no idea why. Derek hadn't gone by that in years. Maybe it was something about being around a ghost?

The ghost pauses. A confused expression crosses his face. "…Derek?"

"Oh, he's a friend of mine," Hiro says. "You've probably seen him once or twice, right?" Hiro gestures to his hair. "Beanie, sort of long hair, wears these crazy lizard gloves and shoes?"

Seriously, SF State is two streets down, and that soup kitchen he makes all of them volunteer at is a two-minute trolley ride away. He knows Derek's walked by this corner at least once.

But you'd think they all would have heard him yammering about it if there'd been an actual freaking comic-book mythological spirit in the area.

The ghost drifts down until his feet touch the ground. Hiro wants to ask about that, too - can he feel the ground beneath his feet? Is he still aware of the pull of gravity or it is just force of habit?

Something about the look on the ghost's face stops him.

It's sad. Regretful. Wistful, even. The ghost looks down at his feet, and the fringe of dark hair over his forehead shadows his eyes. They're faded and transparent, but something about the hue makes Hiro think that at one point maybe they were brown.

"Yeah." The ghost's voice is barely a whisper. "Yeah, I've seen him."

Hiro frowns. He steps a little closer, debating whether to put a hand on his shoulder. Judging by the way the guy reacted last time he tried to touch him, though, Hiro doesn't think it's a good idea to crowd his personal space.

"Are you okay?"

The ghost jerks like he's coming out of a trance, and he backpedals. The green blazer he wears rustles in a breeze that circles the room before dissipating. "Oh. I'm fine. Just… memories. You know?"

"You sound like you've seen a lot," Hiro says cautiously. The ghost shakes his head rather self-deprecatingly.

"No way. Trust me. You can do a lot more than I can from here."

"What do you mean?"

The ghost hesitates. "Um." His form starts to flicker, as if he's getting agitated. The shutters on the windows start shaking. Hiro backs up hastily. "Uh, you don't have to answer if you don't want to-"

(Last time the flickering started, the furniture flew up and broke on the walls. Hiro doesn't exactly want to see the reenactment.)

But the movement stops as quickly as it started. The ghost settles, looking a little embarrassed. "No, no, it's okay. It's just that… I can't exactly leave this place."

Now, that's weird.

"What?" Hiro blurts. "Why?" If he were a ghost, he'd be wreaking havoc. Following his friends around, pulling ghost pranks in the SFIT labs and doing ghostly things-

"I'm - I'm not exactly sure, okay?" the ghost says, bobbing up and down in agitation. "I can only stay by places that I was familiar with when I was alive."

A pause. "And people. People, too."

"… Oh," Hiro says. "That sounds lonely." He can't imagine what it might be like to sit here in this abandoned apartment all the time.

The ghost shrugs transparent shoulders. "I get visitors sometimes. And stores open up on the lower level. Every so often people buy the lot."

"This place has been abandoned for as long as I can remember," Hiro says, squinting.

"... It's been a while," the ghost hedges.

"How long?"

"…"

"Come on! You can't leave me hanging like that!"

"You don't really want to know-"

"-Dude!"

"About thirty years," the ghost blurts out. And then he freezes, like he's said something wrong.

Hiro stares. "Thirty years."

"It's not as bad as it sounds."

"Thirty _years_?" Hiro paces back and forth on the thick carpet, shoes stirring up tiny puffs of dust. "What about before that?"

"Told you. I got visitors. Sometimes. The first four decades or so weren't bad."

Hiro shakes his head in disbelief. "And no one ever talked to you? Or saw you?"

"You're the first."

He stops moving. Plops himself down on the arm of the grimy sofa. "…Wow."

"Tell me about it." The ghost lets out a tiny little laugh. "I still can't believe this is really happening. All of this."

"Yeah, neither can I," Hiro mutters. He jumps to his feet, one hand instinctively going to the mop of hair on his forehead - it's been a habit as long as he can remember.

(He doesn't see the ghost jump a little at the gesture)

"Derek would flip. Actually, so would Sabi. And Honey. And Gogo, for that matter. I mean, would they even be able to see you? The whole," he waves his hand vaguely towards him,"Spiritual messenger thing and all."

"Who knows?" The ghost crosses his arms, but his eyes look more than a little hopeful. "I didn't think anyone would ever know I was here before you ran in."

"Huh," Hiro says. "And to think I don't even know your name."

A pause. The ghost looks more than a little conflicted. "I'll go first, if you want," Hiro offers.

"No, no, it's okay," the ghost says hastily. "My name's Tadashi."

"… Tadashi." It kind of rolls off the tongue. Hiro thinks maybe he's heard it somewhere before-

 _"Tadashi, good timing!" he cheers, and jumps onto the back of the bright red moped. Someone slaps an oversized helmet onto his head_

"-Nice to meet you," he says. "It's Hiro."

—

Stupid, stupid, stupid. Of course he wouldn't remember, of course he wasn't the same person. It was dumb of him to even hope.

(He thought after a hundred years he might finally be catching a break.)

.

.

But then again, maybe it's better this way.

—

Hiro's phone blares techno music, and both of them start.

Hiro fumbles his smartphone, juggles it for a second before tapping the holoscreen.

"Hiro?"

"Oh, heh. Cass?"

His (adoptive) parent sighs on the other end. "Hiro, I'm so sorry. Are you still in class?"

"No," he says. He steals a glance at Tadashi. "Lecture hall ended early - something about an accident in the chemistry labs?"

"Do you mind dropping by the grocery store on your way home, then?" Cass sounds flustered. "The dinner rush is starting, and Dango just got into the dog food again, can you believe it?"

Dango. Hiro swears that he's a bigger pig than Mochi is sometimes, and Dango doesn't swamp the paddleboats when he flops in.

"Yeah, sure." Hiro nods along to the rest of what Cass says, reassures her a couple times, agrees to run some errands. When he finally hangs up, there's an awkward silence.

"Busy?" Tadashi asks. His form wavers a little.

"Yeah," he sighs. "My… mom wants me to help in the restaurant." It feels awkward calling her that. It's barely been a year, after all.

"Oh. I guess you're going, then."

"Yep."

Hiro steps away awkwardly. There's a disappointed but resigned look on Tadashi's face, like he probably should have seen this coming. Hiro suddenly feels a lot more guilty.

"I'll see you around," he offers. Tadashi drifts to the floor. His face lights up a little - hesitant, but cautiously hopeful. "So you'll be back?"

"Hey, I'm a delinquent college student. Takes more than a ghost guy to rattle me." Hiro affects a shrug of the shoulders and casual hair flip. Judging by the way Tadashi smothers a laugh behind his hand, he doesn't exactly pull it off.

"Alright. See you around too then, Hiro."

It's not perfect, but at least they're both sort of smiling now. It's okay for him to leave this guy here. it's totally fine. Right?

Hiro turns. Takes five steps.

He spins and runs back. Tadashi yelps and barely avoids Hiro's flying tackle by shooting six feet up into the air.

"And just what are you doing?" he snaps from on high. The look on his face is one of patented irritation and confusion, and if Hiro hadn't known better, he would have sworn Tadashi was talking to a younger sibling or something. It's exactly like the tone Cass uses on him when she catches him hoarding gummy bears or nursing a sprained ankle or welding rocket boosters to his skateboard, at any rate.

 _Or when he caught you coming home at two in the morning with-_

What?

Hiro rolls onto his back on the floor and grumpily blows his hair out of his face. "Dude, I can't do this."

"Do what?"

"Leave you behind! I mean, I'm like walking off to my non-abandoned house with my non-dead people and you're kinda just standing there with these big sad you-can-ditch-me-here-I-understand eyes-" Hiro falls abruptly quiet. He can feel the blood rushing to his head, and he's sure that his face is bright red. This was a stupid thing to do. He didn't even know what had made him do it. He just hadn't wanted to leave him behind, _couldn't_ leave him behind the second time around

Right. He hadn't thought about it, period. His body had just moved, on his own, before he'd had a chance to think about what he was doing.

Maybe Cass was a little right. Hiro was way too impulsive for his own good.

"Uh. Yeah," he finishes, unsure of what to say.

Tadashi frowns. He floats down from his spot near the ceiling, and he doesn't look angry or annoyed anymore.

"You know," he says thoughtfully. "It's not like this is a new thing for me."

Hiro's feeling more and more humiliated by the minute. He's pretty sure his face could fry an egg at this point.

"I know - Ugh, never mind!" he tosses back. He gets to his feet and stalks off, brushing forcefully at the dust bunnies clinging to his hair.

He's down the stairs, through the ragged drapes overhanging the store entrance, halfway across the lower level when the blue-tinged figure materializes in front of him.

"Whoa, whoa, wait!"

"Leave me alone," Hiro grumbles, and makes to push past him.

He promptly gets something sky blue and emblazoned with the SFIT logo shoved in his face.

"You forgot your hoodie," Tadashi says.

… Oh.

He takes it. Holds it awkwardly. "Thanks. I guess."

"No prob-" Tadashi cuts off mid-sentence to look around. His expression changes from mildly amused to perplexed. "That's weird."

Hiro pauses. Tadashi's eyes flick back and forth rapidly, like he's having trouble focusing. "Are… you okay?"

"No, I'm good," Tadashi mutters. "That's the problem."

He holds up his hand, staring at it like it might disappear any second. And then takes a step back. And then another, and another, and another, until another step would back him up against the glass door of the building-

Hiro hears a static sort of buzz the moment before Tadashi's hand touches the glass. Tadashi winces, jumps away from the door. "Ow. Okay, that's my limit."

Hiro glances between Tadashi and the door. "What's going on? Thought you couldn't go outside?"

"Normally I can't even go this far," Tadashi mumbles. He waves distractedly to a point just past the empty glass display cases. "That's usually when things start to get sort of foggy… and I definitely haven't been able to get to the door. Ever." He throws up his hands in frustration, half-pacing, half-hovering in place. "What's different? Something definitely feels different."

(There's me, Hiro thinks. Of course, he's not sure why a random kid that just happened to hide in an empty lot to escape a bunch of bullies might be able to do anything.)

"Maybe it's visitors?" Hiro offers. "You haven't - um, seen anyone in a while."

This is so not his forte. Hiro's an engineer, he's a builder. He's not like Honey or Wasabi or Derek, he doesn't do the whole talking-to-people thing.

(At all, really.)

It's the thought that counts, right?

"Maybe," Tadashi mutters. He sounds unconvinced. He glances at Hiro again, and why does it feel like he's looking through him, looking at someone else not quite the same but not very different either-

"Can you do me a favor?" Tadashi says. "Just, um. This might be awkward. Just come over here."

"… What are you planning."

"Just get over here, Hiro. Please?"

"Don't do anything creepy," Hiro deadpans, and walks over to stand in front of Tadashi. They're barely two feet apart now, and he definitely notices Tadashi's transparent eyeroll.

"Calm down, bonehead. It's not like that."

But something's different - even Hiro notices it. Maybe Tadashi was pale blue and see-through when he first saw him, with a form that flickered every few minutes and always seemed a tiny bit too blurry at the edges, but he looks… different. Not in terms of physical characteristics, but he's more colorful. His blazer is a definite shade of dark green, and his skin is more peach than periwinkle.

But none of that is anything compared to Tadashi's expression, which slowly turns from confused to amazed in the space of a few seconds. Tadashi lets out a tiny breath of disbelief. "No way," he mutters. "You're like them."

"Like who, now?"

"The others- the people I used to know." Tadashi cautiously reaches out, and Hiro jumps a little, but Tadashi just waves his hand a few inches in front of his face. Like Tadashi's the one that's real, and Hiro's the ghost. "You're _warm_."

He says it like it's something special, but Hiro just thinks it's weird. Well, yeah, he's warm. Humans are warm-blooded. Why's he making such a big thing out of this?

"Hiro, you remember when I told you I could only stay by people I was close to when I was alive?" Tadashi wrings his hands, and there's something that looks a little like desperation in his eyes. "Those were people like my aunt. My best friends, my -" He cuts himself off abruptly, and Hiro's pretty sure he's heard enough, anyways.

"Hold up," Hiro blurts out, and he's pretty sure he knows where this is going. And no. No. No freaking way. Not just because he's barely known the guy for all of half an hour or because he's seen too many ghost flick horrors.

"Are you asking me for permission to _haunt_ me?"

He sees Tadashi's eyes go wide in shock, and the ghost backpedals. "I'm not!" Tadashi says hastily. "Definitely not."

Then _what_ , Hiro wants to ask, but he can't seem to get the words out.

It's just-

 _You can't._

 _It's starting._

 _Can't let it happen again-_

"Are you okay?"

Hiro blinks wildly, startled back to clarity. It's Tadashi saying it now, hovering hesitantly in front of him. At some point they had switched places - now it was Hiro hanging onto the knob for support, bracing himself against the glass door like a trapped animal. His muscles are coiled and tense. It takes a conscious effort to relax them.

"Um," he manages.

 _Go, get out of here-!_

(Why did that voice sound so similar to his own?)

"I need to leave," Hiro says, his voice thick and unfamiliar in his own ears.

"What? Why?" Tadashi takes a step closer. He looks concerned and confused and Hiro violently shakes his head, too-conscious of the pain building in his skull.

 _Talking makes it worse._

"No, don't say anything. Just-" He backs up, fumbling with one hand for the knob. After a couple of seconds of pushing fruitlessly against the glass, Hiro pulls on it hard-

And suddenly he's outside, blinking away the black spots crowding his vision in the sudden surge of light. Inside, there had been peeling paper sheets that had mostly covered the windows and left stray sunbeams to stream in around the cracks. Outside, the afternoon sun is bright and merciless and Hiro doesn't care at all, he's running before the last of the splotches fade.

He's three blocks away before he starts to slow down, but when Hiro thinks back on it later over cold chicken wings and a concerned Cass, he's not entirely sure why he was running in the first place.

(Tadashi knows, though, and he wonders why he ever hoped things could be different this time around.)

* * *

 **A/N: What I basically had in mind for this plot - In the original post-movie timeline, the first Hiro and Nerd Lab discover that Tadashi's returned as something not quite human but not really dead either. They decide to help him move on, which... ends pretty traumatically for all of them. In short, everyone but Aunt Cass ends up dead, and unlike Tadashi, they're not coming back. Wracked with guilt, Tadashi hardly protests when he realizes that he's stuck here indefinitely.**

 **He figures he kind of deserves this fate, anyways.**

 **Except apparently that's not the end of it, because even ghosts have their inner demons, and Tadashi's have all returned, in the flesh. Literally.**

 **Tadashi can't work out whether that's a good thing or not.**


End file.
